The state Department of Children and Families had been notified that an autistic Hartford teen who died this week weighing 84 pounds and suffering from bruises, broken ribs and cuts had not been attending school, according to officials from state and local agencies.

DCF and the Office of the Child Advocate are now conducting investigations into the child-protection agency's dealings with Matthew Tirado and his family. Matthew's mother, Katiria Tirado, 33, was charged with cruelty to persons Wednesday following the 17-year-old's death. The cause of death has not been determined.

Matthew Tirado had been a student at Oak Hill School in Bristol, which serves students with moderate to severe disabilities. But the staff had not seen him in more than a year, said Barry Simon, president and CEO of Oak Hill.

School officials had reported his prolonged absence to DCF and the Hartford school district, which was responsible for the city resident's education.

"We were informed that the mother had chosen to not have him come to our school any longer," Simon said Thursday afternoon.

DCF released a statement from Commissioner Joette Katz confirming that the agency had involvement with the family.

NBC Connecticut / Pool

Katiria Tirado, 33, appeared in court Thursday on a cruelty to persons charge that came after the death of her 17-year-old son Matthew.

Katiria Tirado, 33, appeared in court Thursday on a cruelty to persons charge that came after the death of her 17-year-old son Matthew.

(NBC Connecticut / Pool)

"We are working closely with law enforcement in their investigation and have taken steps to ensure the proper care of the boy's sibling. As is our standard practice when a death occurs in an open case or a case that recently closed, we are conducting a thorough review of our work," the statement from Katz read.

Gary Kleeblatt, a DCF spokesman, said the agency had investigated whether children in the family were attending school. Kleeblatt said the mother would not allow DCF staff access to the home and refused to engage in services or accept the attempts of the department to help the family.

The case was closed last month, Kleeblatt said. There were no indications of safety concerns involving Matthew or other children in the home until this week, Kleeblatt said.

Hartford police said Thursday that Katiria Tirado's 9-year-old daughter is in DCF custody.

"It's a shocking, sickening tragedy of a child who was completely dependent on adults and the community and public system to protect him," Eagan said. "Our role at the [Office of the Child Advocate] and the child fatality review panel is to examine how such a tragedy could have occurred and how a child of his age can be found in such a devastating and shocking condition. All children are vulnerable but a child with significant disabilities, who is unable to advocate on his own behalf, is particularly vulnerable to abuse."

In a court appearance Thursday, Katiria Tirado listened as a judge pointed to an arrest warrant that indicates "injuries that are significant and are consistent with a pattern of abuse and neglect."

Superior Court Judge Omar Williams ordered Tirado, who is charged with cruelty to persons, held on a $200,000 bail.

Matthew's father, Pedro Gomez, was among family, some of whom cried quietly, that watched nearby as the judge discussed the case.

"I want to know what happened," Gomez said outside court Thursday. "I want to know what happened if she did [it]. That's all I want to know."

Matthew's family, some vocally angry or sad, had said that Katiria Tirado had not let them see the teen.

Velazquez said she didn't know if he had been attending school, but questioned why no one, be it the state or even a neighbor, stepped in.

Just before 3 a.m. on Tuesday, city emergency dispatchers received a 911 call from Katiria Tirado asking for an ambulance for her son, who she said was vomiting and had gallstones, according to police.

Within several hours, staff at Hartford Hospital had pronounced the boy dead. A medical examiner, who contacted city detectives later that day, noted Matthew's 5 foot 8 frame weighed 84 pounds and had bruises and cuts, the warrant for Katiria Tirado's arrest states.

The medical examiner also discovered that three of Matthew's ribs had been broken, an old injury, according to the warrant.

When investigators reviewed some photographs on the mother's phone, they reported seeing that the cabinets and refrigerator had been locked shut in her Park Street apartment, which she shared with Matthew, the warrant read.

Katiria Tirado told detectives that Matthew, of whom she was the sole caregiver, had begun to rapidly lose eight about a month before his death, the warrant states. She told them she did not bring him to get medical attention, but gave him weight-gaining protein powder in addition to his regular diet.

She said he continued to lose weight.

Tirado told investigators that Matthew began throwing up Saturday night but improved the next day before he began to vomit again Sunday night.

She searched his symptoms on Google and gave him Pepto-Bismol, the warrant said.

By 3 a.m. Monday, she had called and texted her sister asking if she could watch Matthew's sister while she brought him to the hospital, the warrant read. She told investigators that her sister couldn't watch the child, so Tirado didn't bring Matthew to the hospital.

She told investigators that his condition continued to worsen and his vomit turned a dark color, which her internet searches revealed may be caused by blood and related to gall bladder issues, the warrant read.

She said she found a neighbor to watch her daughter and called for the ambulance.

Detectives reviewed the phone and found texts that supported her claims, but also found the photos, the warrant said.

After questions from detectives, Tirado eventually said that her son would eat until he got sick, the warrant read. She told investigators she moved food she didn't want her son to eat into the locked cabinet and also locked the refrigerator, the warrant read.

She told investigators that she personally would provide Matthew the food he would eat daily, the warrant read.

Tirado said that after Matthew's death, she removed the locks before investigators came to her home, according to the warrant.

They asked why and she said: "I no longer need them," the warrant said.

When they asked about the injuries, Tirado said a bruise above his buttocks was from him sitting a lot and that a speaker fell on his face, causing the cut above his left eye, the warrant said.

The warrant said she offered investigators no explanations for other reported injuries.

Police said Thursday that Matthew's cause of death is pending further study by the medical examiner's office.